a) Field of the Invention
The present invention relates to a charging assembly for introducing a product, especially a fluid, into a mixing vessel. The invention further relates to a mixing vessel comprising such a charging vessel in various configurations.
b) Background Art
Mixing or reactor vessels are used predominantly in the chemical and pharmaceutical industries for various operations including reacting or mixing ingredients. The ingredients can be mixed, heated, emulsified, suspended or subjected to gasification. A conventional standard vessel is shown in FIG. 1 which comprises a single stirring element or agitator 7 connected to a drive shaft 1. The drive shaft 1 is disposed along the center axis of the vessel and is set in rotary motion via driving means 20. The driving means normally comprises a motor 8 connected via a transmission 9 to the drive-shaft 1. Such reactor vessels also often include a baffle assembly 4 provided to cause flow disruption to improve mixing. Such vessels are often designed to have a glass or enamel coating on all components exposed to the materials being processed. The glass coating ensures protection against potentially corrosive or abrasive ingredients.
A problem associated with such vessels, especially vessels of smaller size, is that the number of ports required for any given process is not sufficient. This is particularly the case for glass-coated vessels. The coating process requires the ports to protect from the vessel taking up more space as compared to conventional inset ports commonly used in the construction of steel or refined steel containers. In addition, compared to steel vessels, it is much more difficult to provide additional ports in the cylindrical portion of a glass-coated vessel. It is therefore the object of the present invention to provide an improved mixing vessel with additional charging means.
According to the present invention, a novel charging assembly for introducing a fluid product into a mixing vessel is provided. In addition, mixing vessels are provided which make use of the charging assembly.
The charging assembly comprises a stirring mechanism which includes a drive shaft extending into the vessel from above through a top port. An agitator is connected to the lower end of the drive shaft, which is actuated by driving means connected to the upper end of the drive shaft and disposed above the top port of the vessel. According to the invention, an adapter element is connected between the driving means and the top port and is disposed about an upper portion of the drive shaft extending out of the vessel. The adapter element surrounds the drive shaft to create an annular space therebetween. The adapter element further comprises at least one inlet port for introducing a product into the annular space along the drive shaft and thereafter into the vessel. The adapter may also comprise connections for the provision of sensors, control devices, viewing ports, etc.
In a preferred embodiment, the charging assembly further comprises a feed tube connected to the top port, which extends downwardly about the drive shaft toward the direction of the agitator. The feed tube and the drive shaft are arranged along a common axis and define an annular passage therebetween, which is in fluid communication with the annular space of the adapter. The length of the feed tube is selected such that it ends in the region above the agitator. The spacing between the end of the tube and the agitator can be selected depending on the process requirements.
The provision of the adapter element integrated into the conventional stirring mechanism allows for an additional inlet port at the top of the vessel. Apart from increasing the length of the drive shaft, no alterations are necessary to the conventional stirring mechanism. The adapter element can be easily retro-fitted into existing vessels thereby providing an additional input port.
Further advantages are achieved by feeding the charged product along the drive shaft in downwards direction and directly onto the agitator. The product to be added is supplied to the higher energy mixing zone in the vicinity of the agitator. This allows shorter mixing times and is particularly advantageous when the ingredients to be mixed have different viscosities. By introducing the product directly to the agitator, it is also possible in some instances to do away with the conventional disruption baffle.
Further objects and advantages of the present invention will become apparent in the following description of preferred embodiments taken in conjunction with the drawings.